Optical fiber sensor

An optical fiber sensor comprising

• a light source;
• an optical fiber including a core having a plurality of short-period gratings whose periods are different from each other, and a cladding for covering the core;
• and
• a light receiving unit for detecting an intensity of light that has been inputted into the optical fiber from the light source and passed through the short-period gratings;
• wherein transmission-loss wavelength ranges of the plurality of short-period gratings under a cladding propagation mode are continuous, and include an entire light-emission wavelength range of the light source.

An optical fiber sensor comprising:

• a light source;
• an optical fiber including a core having a short-period grating, tilted with a continuously varying angle and a region where the refractive index is different from that of the core being curvedly provided, and a cladding for covering the core;
• and
• a light receiving unit for detecting an intensity of light that has been inputted into the optical fiber from the light source and passed through the short-period grating.

An optical fiber sensor comprising:

• a light source;
• an optical fiber including a core having a short-period grating whose tilt angle gradually varies in a direction of a central axis of the optical fiber, and a cladding for covering the core;
• and
• a light receiving unit for detecting an intensity of light that has been inputted into the optical fiber from the light source and passed through the short-period grating.